Where can I find the email notification defaults for users? I’m trying to figure out what the default settings for email notifications are for community users / specific categories.
Context: I moved some old posts from another category to another and users got multiple email notifications. I’m trying to figure out how many users are affected and how to understand how email notifications work going forward.
If you’re moving topics from one category to another there is the disable category edit notifications admin setting you can toggle on which should skip sending out notifications for those. (particularly useful for tidying up ) 
There are some sitewide user defaults you can check in the User Preferences tab of the admin settings (the email ones, as well as if you have any categories or tags set to ‘Watching’, etc by default) - though these are only the defaults and users can set their own.
The email logs /admin/email/sent are a good place to see what emails actually got sent out (and the other tab for skipped is useful too to see who got a notification but no email).
Hopefully some of that is helpful.
There’s also disable tags edit notifications too ↩︎